Frost Dates: First and last frost dates for St Louis Sci Ctr, MO

ℹ️ How to read these charts for the spring

As spring unfolds, the risk of frost gradually decreases each day until your tender plants are finally safe. The probabilities shown in the chart help you make smart decisions about when to plant.

While frost typically forms at 32°F, tender plants can be damaged even when temperatures are slightly higher. Air temperatures are often measured several feet above the ground, but temperatures at plant level can be several degrees colder. Protected areas like porches help by blocking radiational cooling. Given these variables, we consider 36°F the "caution zone" for frost-sensitive plants.

Key dates for your spring planting:

  • By May 7, you have a 90% chance of being frost-free — this is your "safe date" for planting tender crops
  • Around April 17, there's a 50/50 chance of frost — check weather forecasts carefully if planting now
  • Before April 3, there's still an 80% risk of frost — too early for tomatoes and other tender plants unless you're prepared to protect them

If the 10-day forecast shows no temperatures below 40°F, you might safely plant earlier than the above dates suggest. Many gardeners watch for this weather window to get a head start on the growing season.

In the Spring
Temperature 10% 20% 30% 40% 50% 60% 70% 80% 90%
Last 16° Mar 15 Mar 6 Feb 28 Feb 23 Feb 18 Feb 13 Feb 8 Feb 1 Jan 24
Last 20° Mar 23 Mar 15 Mar 9 Mar 4 Feb 28 Feb 23 Feb 18 Feb 12 Feb 4
Last 24° Mar 29 Mar 23 Mar 18 Mar 14 Mar 11 Mar 7 Mar 3 Feb 27 Feb 21
Last 28° Apr 9 Apr 3 Mar 29 Mar 25 Mar 22 Mar 18 Mar 14 Mar 9 Mar 3
Last 32° Apr 26 Apr 20 Apr 15 Apr 11 Apr 7 Apr 3 Mar 30 Mar 26 Mar 19
Last 36° May 7 Apr 30 Apr 25 Apr 21 Apr 17 Apr 12 Apr 8 Apr 3 Mar 27

ℹ️ How to read these charts for the fall

As summer ends in St Louis Sci Ctr, MO, nighttime temperatures begin to drop, and your risk of frost increases with each passing day. Knowing when to expect frost helps you harvest sensitive crops and extend your growing season with protection methods.

The chart below shows the probability of experiencing specific temperatures on various dates. Here's what this means for your garden:

1
Early warning: Around October 19, there's a 20% chance of 32°F — start monitoring forecasts and have plant covers ready
2
Decision time: By October 29, there's a 50% chance of frost — harvest tomatoes, peppers, and other tender crops or prepare protection
3
Last chance: By November 9, there's an 80% chance of seeing 32°F — most tender plants will be damaged without protection
4
Another perspective: You have only a 1 in 5 chance of making it past November 9 without a freezing night

These probabilities help you time your end-of-season harvests and know when to apply protective measures like row covers, cloches, or cold frames to extend your harvest.

In the Fall
Temperature 10% 20% 30% 40% 50% 60% 70% 80% 90%
First 16° Nov 22 Nov 28 Dec 3 Dec 7 Dec 11 Dec 14 Dec 18 Dec 23 Dec 29
First 20° Nov 11 Nov 17 Nov 22 Nov 25 Nov 29 Dec 2 Dec 6 Dec 10 Dec 16
First 24° Nov 3 Nov 9 Nov 14 Nov 17 Nov 21 Nov 24 Nov 28 Dec 3 Dec 9
First 28° Oct 25 Oct 31 Nov 4 Nov 8 Nov 11 Nov 15 Nov 19 Nov 23 Nov 29
First 32° Oct 13 Oct 19 Oct 23 Oct 26 Oct 29 Nov 1 Nov 5 Nov 9 Nov 14
First 36° Sep 28 Oct 4 Oct 9 Oct 12 Oct 16 Oct 19 Oct 23 Oct 28 Nov 3

📍 Frost Dates for other nearby locations

Or enter a new zipcode:

Data is provided by the NOAA National Centers for Environmental Information.